The present invention is related to a mobile telephone user interface, and particularly to the control of mobile telephone functions by means of a keypad included in the user interface during different states of operation in which a mobile telephone may operate from the standpoint of a mobile telephone system.
Manufacturers attempt to equip mobile telephones with a versatile user interface that allows the user to easily control mobile telephone functions. An essential part of the user interface of a modern mobile telephone consists of a sufficient selection of keys and a display that operates together with the keypad. To make key operation easy, the most important functions have their own keys or clearly arranged groups of keys. Therefore, in addition to actual telephone keys, or numeric keys and * and # keys, a mobile telephone usually has SEND and END keys for placing and controlling a call, display control keys, such as a CLEAR key, keys for browsing through menus and selecting different functions and settings, and a key or keys for adjusting the volume of the earphone. On the other hand, manufacturers in the field of mobile telephones also are attempting to develop products that are as simple as possible, and to that end, to reduce the number of keys to a minimum. Therefore, a mobile telephone that has been designed to be as inexpensive and simple as possible may have only the above-mentioned telephone keys, SEND and END keys, and a power switch. This requires solutions which preserve the versatility of the user interface regardless of the minimal number of keys.